A Study On The Diffusion And Extinction Of Non-spherical Particles Under Different Wind Conditions

The attenuation of electromagnetic wave in the atmosphere is a very complex process,and the diffusion of air pollutants exert a significant impact on the transmission of the electromagnetic wave to a measurement at a specific location using the laser rader,and the investigation on the spatial-temporal distribution of this impact is relatively lacking.Therefore,in this paper,we used MP-PIC method to simulate the diffusion of a point source that injected particulate pollutants.After obtaining the temporal and spatial distribution of the particulate pollutants,the effects of different parameters such as particle shape,incident wavelength,particle rotation axis direction,polarization direction of incident electromagnetic wave,and axial ratio change on electromagnetic wave attenuation are further analyzed.The major conclusions achieved in this thesis are as follows:(1)At a low wind speed condition(2m/s),the influence area of the attenuation coefficient is divided,and the influence range along the vertical direction is larger than that in the horizontal direction;when the wind speed reaches 5m/s,the influence radius in the vertical direction is approximately the same as that in the horizontal direction;when the wind speed reaches 10m/s,the influence radius in the horizontal direction is larger than that in the vertical direction.In addition,the distribution of the influence area of the attenuation coefficient is non-uniform under the condition of the low wind speed,and there exist high value areas under the condition of 2m/s and 5m/s wind speed.In contrast to that,the distribution of the attenuation coefficient is relatively uniform under the condition of the 10m/s wind speed.(2)The variation of the attenuation coefficient is proportional to the injection rate and the wind speed.The attenuation coefficient increases with the increase of the injection rate and the wind speed.(3)The scattering ability of the particles in new material is the smallest when the incident wave length is 5cm,and the largest when the incident wavelength is 2cm.Moreover,the absorption ability is the worst when the incident electromagnetic wavelength is 2cm,and the best when the wave length is 10 cm.Under the same conditions,the attenuation coefficient of the pollutant is the largest when the wavelength of the incident is 2cm,and the smallest when the wavelength is 10 cm.(4)The attenuation coefficient of oblate ellipsoid particles is larger than that of oblate ellipsoid particles,and the attenuation coefficient of the oblate ellipsoid particles increases with the increase of the axial ratio,and the attenuation coefficient of the oblate ellipsoid particles decreases with the increase of the axial ratio.(5)The polarization of the incident wave and the orientation of the particle rotation axis have a significant impact on the attenuation coefficient.